Reduction drive mechanism



Feb. N, 1936. M. c. HOXIE REDUCTION DRIVE MECHANISM Filed May 17, 1955 Inventor: Merrill C.Hoxie,

His Attorne M Law/f2 mo I \AAAAN\\\\\\\\\\\\\ m. H? A Patented Feb. 11, 1936 UNITED STATES- PATENT OFFICE REDUCTION DRIVE MECHANISM New York Application May17, 1935, .Serial No. 22,010

9 Claims.

My invention relates to drive mechanisms, and

more particularly to drive mechanismsadapted foruse in connection with the operation of electrical circuit elements, such, for example,-as the tuning elements of radio receivers.

My invention has for one of its objects to provide a drive mechanism for operating a driven element at reduced speed with respect to the speed of the driving member, and which is of extremely simple, rugged, compact and of economical construction.

A further object of my invention isto provide a reduction drive mechanism which possesses the above characteristics, and which at the same time operates free from back lash, lost motion,-

or undesired play between its different component parts.

An additional object of my invention is to provide such a reduction drive mechanism in combination with means whereby direct drive may also be obtained while substantially retaining the simplicity, compactness, ruggedness and economy of the apparatus, and which at the same time operates free from undesired play, or lost motion,

2 1. at either of the twooperating speeds.

A still further object of my invention is to provide a dual drive mechanism having the above advantages and which, when operated for drive at either of its two speeds, the connection for operation at the other speed is completely broken, thereby to remove any drag between components of the mechanism.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims.

itself, however, both as to its organization and the method of operation, together with further objects and advantages thereof, willbe best understood by reference to the following specification taken in connection with the accompanying drawing in which Fig. 1 is a side view partially in section of a mechanism embodying my invention; Fig. 2 is an end view of the arrangement shown in Fig. 1; Fig. 3 is a detailed cross-sectional view Lr-of certain elements embodied in my improved mechanism; Fig. 4 is a cross-sectional view showing a modified arrangement of the component parts of my improved mechanism, and Fig. 5 is a detail view of certain of the elements shown in 9 Fig. 4.

Referring to Fig. l of the drawing, I have shown one embodiment of my invention in whicha step-shaped bearing. member I is mounted on a panel 2 by meansof a nut 3 threaded on one end My invention x ofzthe bearingand held. in place bya lockwasher 4. A drivingor control member in the-form of a shaft 5 is journaled in the bearing I for axial and rotatable movement with respect thereto. A suitable knob (not shown) is mounted on one end of the shaft 5 for actuating the shaft to adjust the tuning, or driven devices. A retaining ring 6 resting in a groove 1 cut in the shaft 5 is provided as a stop for retaining the shaft 5 in the bearing member I. A driven member comprising a pulley 8 having an enlarged cup-shaped portion. 9 and a belt groove I0 is rotatably mounted on the bearing I adjacent the panel 2. The devices to beccontrolled are belted to the pulley 8 by means of a-belt II resting in the groove Ill. The enlarged cup-shaped portion 9 of the pulley 8 is provided with a roughened-knurled, or toothed surface I2 around its outer periphery which is adapted to be engaged by resilient inwardly biased spring arms l3 of a U-shaped member. I4 fixedly mounted on one end of the driving member 5. Stamped projections I5 are provided at the outer extremities of the arms I3 which engage the teeth IZ when the shaft 5 is axially shifted to a position such that the ends of the arms I3 overlap the periphery of the cup-shaped portion 9 of the pulley 8. A raised ridge l3 extends .around the circumference of the cupshaped portion 9 which serves to retain the projections I5 on the arms I3 in engagement with the toothed surface I2 when the parts are in the direct drive position. In this manner the component parts of the mechanism are retained in the selected driving position by the ridge I3"; The position of the elements of the mechanism for direct drive is shown in detail in Fig. 3.

It will be seen that to drive the pulley 8 directly from the shaft 5, the shaft is axially shifted tothe right until the stamped-projections I5 on the arms I3 ride over the ridge l3 andengage the teeth I2 on the periphery of the cupshaped portion 9, in whichposition the drivingmember may be rotated and a one to one driving ratio is established between the shaft and the pulley.

Inaccordance with my invention, I provide a reduction drive mechanism for driving the pulley 8 at aspeed less than the speed of the shaft 5. This reduction drive mechanism includes a resilient, deformable and normally annular member I6 mounted on the pulley 8 by means of resilient arms IT. The resilient member I6 is normally concentrically disposed in radiallyspaced apart position with respect to an annular member I8, .which is fixedly mounted about they outersurface of the stationary bearing member L? of the resilient member I6. If desired, the member IBQmay be dispensed with, the'outer metallic surface of the member I being enlarged and roughened to present the desired friction to the inner surface of the member I6. As shown. in

.detail in Fig. 3, the internal diameter of the resilient annular member IE is slightly greater.

than the peripheral diameter of the annular friction member I8; By this arrangement the annular member I6 is maintained out of contact with the friction surface I9 when the driven member 8 is directly coupled to the driving member 5.

The arms I3 retain friction brushes .29 in engagement with the outer periphery of the annularmember I6 when the driving member 5 is axially shifted to the left. In this position the projections I5 of the arms I3 no longer engage the surface I2 of the cup-shaped portion 9 of the pulley 8, but instead press members 29 against the outer surface of member I6, thereby deforming the member I6 and pressing its inner diametrically opposite surfaces into engagement with the outer surface of member I8. It will of course be understood that the friction brushes 20 may be replaced by rollers, or balls, mounted on the arms I3 in any suitable manner.

' To establish a reduction. drive through the mechanism described above for fine adjustment of the devices to be controlled, the shaft is axially shifted to the position shown in Fig. 1 of the drawing in which position the projections I5 are disengaged from the teeth I2 of the cupshaped portion 9 of the pulley 8. As the shaft 5 is shifted to accomplish this disengagement, the resilient arms I3, which are normally biased.

toward each other, contract to press the friction brushes 29 against the resilient member I6 thus, forcing segments of the internal surface of the 5 member I6 into substantially nonslipping engagement with segments of the friction surface I9 of the member I8. This operating position of the mechanism is also shown in Fig. 2, where it will be seen that the normal circular contour of the resilient member I6 is deformed into an elliptical shape. With the elements of the mechanism in this position, rotation of the shaft 5 causes the brushes 29 to slide over the external surface of the resilient member I6 thereby to ly connected to the pulley 8 this advancement of portions thereof around thefriction surface I9.

press successive segments of the internal surface thereof into substantially nonslipping engagement with successive segments of the friction.

surface I9. Since the internal diameter of the member I6 is greater than the diameter of the friction surface I9 the sliding movement of the brushes 20; over the external surface of the resilient member I6 causes the free portions of the resilient member to be advanced around the pe- Thus, for each starting point on the friction surface I9 .to a

second point on the friction surface I9 displacedfrom the starting point by a distance equal to thedifference between the internal circumferential length of the resilient member I6 and the outer circumferential length of the friction surface I9. Since the resilient member I6 is direct- 8 is proportional to the ratio between the internaldiameter of the resilient member I6 and the diameter of the friction surface I9;

In the use of my improved dual control mechanism for adjusting electric circuit tuning devices it will be understood that a rough adjustment may first be obtained by shifting the shaft 5 to the right, thereby directly coupling the driving and driven members in the manner hereinbefore explained, and turning the driving, or con trol, member 'until an approximate adjustment is obtained. The driving member is then axially shifted to the left to establish the reduction driving connections and rotated until an exact adjustment is obtained. 7

,While in Fig. 1 I have shown the resilient member it connected to the cup-shaped member 8 by the resilient arms I'I, it will be readily understood that other connecting arrangements be tween these two elements may be employed:

Thus, in Figs. 4 and 5, I have shown a connection.

in which the resilient member I6 is a cylinderhaving an external diameter slightly less than the diameter of the innercylindrical portion 9 of the member 8. Depressions 2| are provided around the circumference of the right-hand por-,

tion of the resilient member which are arranged to engage depressions 22 stamped inwardly around the circumference of the cylindrical portion of.

the member 8. The coaction between the depression 2i and 22 is such that when the stamped projections 15 of the resilient arms 13 are in engagement with theteeth I2 thus establishing a one to one driving connection, as shown in Fig. 3,

the resilient member I6 is loosely held in position as shown in Fig. 4. It will be seen that in this position the depressions 2I' and 22 are'in a loose engagement which is just sufficient to retain the resilient member I6 connected to the member 8., When the driving member 5 is shifted axially to.

surface of certain of the depressions 2| positively to engage the outer surface of the depressions 22 as shown in detail in Fig. 5. This locking action between the depressions 2| and 22 is transferred between successive sets thereof as the brushes.

20 are rotated around the resilient member I8, thereby maintaining a positive connection betweenthe member I5 and the pulley 8 during the reduction drive action.

It will be observed that the device as described above is capable of operation to drive the driven.

member 8 at either of the two speeds provided without any appreciable lost motion, back lash or undesirable play of any type. Any lost mo tion which might occur in the device would be due to distortion of one of its members, such as edgewise distortion of the member I4 and arms I].

This, however, can readily be completely eliminated by making the member I4 and the arms I! sufficiently rigid to effect the desired driving op- It has been found that such rigidity can be obtained without eration without such distortion.

making the member l4 and the arms ll of undesirably large dimensions. By employing the. con-..

nection between the members I6 and 8 shown in Figs. 4 and 5 backlash or lost motion between these i members is completely eliminated.

The ratio of movement of the driving and.

driven members obtainable :-with aldevice concrements of said resilient member around said friction surface and for pressing successive sets of 'said-second-named depressions into positive engagement with successive sets of said first-named depressions thereby to impart rotary movement to said driven member duringrotation of said driving member.

8. The combination, in a dual drive mechanism, of a' driving member, a driven member, a stationary friction surface, a resilient member surrounding said friction surface and normally spaced therefrom, said resilient member being fixedly attached to said driven member, an arm attached to said driving member arranged in one position to engage said driven member to establish a direct drive connection between said driving and driven members, and in a different position thereof to press a portion of said resilient member in contact with said friction surface to establish a reduction drive connection between said driving and driven members, and means including said arm so arranged that when either of said connections'is established the other connection is completely broken whereby either connection operates free from drag through the other connection. a

9. In a dual drive mechanism, a driven member, a driving member axially and rotatably mov able with respect to said driven member, a stationary friction surface, a resilient member surrounding said friction surface and connected to said driven member, means including a resilient arm mounted on said driving member for directly coupling said driving and driven. members in one axial position of said driving member, and means including said resilient arm for advancing successive increments of said resilient member around said friction surface during rotation of said driving member whenrsaid driving mamber is shifted to another axial position, said resilient member being completely disengaged from said friction surface in the direct drive position of said driving member.

MERRILL C; HOXIE. 

